def else_test():
	s = input('请输入除数：')
	result = 20 / int(s)
	print('result is -->', result)


def right_main():
	try:
		print('try 代码无异常')
	except:
		print('程序出现异常')
	else:
		else_test()

def wrong_main():
	try:
		print('try 代码无异常')
		else_test()
	except:
		print('程序出现异常')
	else:
		print('this is else block')

wrong_main()
# right_main()